1. Field of the Invention
This invention relates to a housing for an electrical module of a battery pack for a motor vehicle and associated battery pack.
2. Description of the Related Art
According to the invention, a “cell” designates a single electrical device capable of producing electric current. A cell can typically produce a voltage of between 2 and 4 volts, generally 3.7 volts, and is generally designed to be associated with other cells, assembled in series, to supply a higher voltage.
A cell may have a rigid or flexible envelope. In the latter case, we speak of a “pouch cell”.
A “module” designates a set of several cells having a self-supporting rigid structure, this self-supporting rigid structure consisting either of a single rigid envelope containing several cells with flexible or rigid envelope, or of the assembly of several cells with rigid envelopes, placed beside each other.
Lastly, a “battery pack” designates an electrical assembly containing at least one module and the heat-regulating means for this module, consisting of at least one heat-regulating plate.
The heat-regulating plate is generally cooled, and therefore cooling for the module. It may nevertheless be used, at least temporarily, to heat a module in order to bring it to optimum operating temperature when the climatic conditions are unfavorable. The heat-regulating plate may comprise internal channels circulating a heat transfer fluid.
U.S. Patent Publication No. 2010/0025132A2 describes electric cell modules, equipped with cooling means which may consist of cooling plates maintained at a temperature of below 43° C., heat sinks or systems circulating cold air from the vehicle main cooling circuit.
In this type of assembly, the quality of the contacts between the modules and the cooling plates must be excellent. However, this result is difficult to achieve since it implies that the dimensions of the cells and the cooling means must be highly accurate, which is generally not the case. In addition, dimensional variations of these constituents may appear or increase during the life of the battery pack. Consequently, a simple stack, as proposed in the state of the art, does not provide the conditions required for optimum heat conduction between the modules and the cooling means.
Faced with a problem of heat conduction between two surfaces, it is also known to insert a heat-conducting interface between these surfaces, such as a heat-conducting film, sometimes called a “thermal pad”. An example of such a thermal pad is a silicone film having a ceramic load, which improves the heat conduction between each cell and the cold plate by compensating for small flatness or alignment defects of the lower wall of each cell of the module and flatness defects of the cooling plate. However, these compensations are approximately one tenth of a millimeter, which is not sufficient to compensate for contact defects in all cell assembly configurations. In addition, these compensations using a heat-conducting film still depend on whether or not the cooling plate is properly tightened against the cells.
There is therefore a need for an efficient solution to tighten the cooling plate against the module whose temperature it is supposed to regulate.